Universal end of arm robot tool

ABSTRACT

An end of arm tool subassembly includes three identical linear drive mechanisms connected directly together to provide three directions of movement. Each linear drive mechanism includes a base defined by a longitudinal axis and a slide movably coupled to the base. The base has at least one mounting surface disposed parallel to the longitudinal axis and an end mounting surface disposed perpendicular to the longitudinal axis. The slide traverses in a direction parallel to the longitudinal axis and has a slide mounting surface thereon. One of the identical linear drive mechanisms is directly attached to the end mounting surface of the base of another linear drive mechanism to provide two of the three directions of movement.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/069,441, filed Oct. 28, 2014, and U.S. Provisional Application No.62/139,856, filed on Mar. 30, 2015, and U.S. Provisional Application No.62/210,019, filed on Aug. 26, 2015, which are incorporated herein byreference in their entirety for all purposes.

BACKGROUND

Industrial manufacturing faces many challenges in making consumerproducts faster, better and cheaper. As a result, manufacturerscontinuously explore the feasibility of assisting manual labor withautomated tools. Such devices include, among others, computer controlledhandling systems, which may pick and place parts in and out of processmachines faster, more accurately and, therefore, increase the productionthroughput and the quality of the part.

While responding to market needs, manufacturers also need to makeprovisions for fast product changes on the same production line. Whilemanual labor can easily adapt to such changes, automation tools must bephysically reconfigured. Such reconfiguration results in down time,which in turn elongates the payback period of the tool.

In order to reduce down time, as result of tool changes, manufacturersare continuously searching for intelligent tools, which may bereconfigured upon controller command in a very short time and,therefore, quickly handle a need for a product change. Such a tool issometimes referred to as an Intelligent End of Arm Tool (iEOAT).

iEOATs are gaining increased popularity among automotive manufacturers.This is because, in a typical automotive assembly line, exterior bodyparts, such as hoods, roofs, doors and wheels, can change from one carmodel to another. Such changes can involve changes in shape, color,size, texture. Accordingly, the tools that handle these parts musttherefore change with it.

Automotive body parts are usually welded to each other in theirmanufacturing process. The body parts, which are being joined togetherare positioned along the assembly line in frames, fixtures or held by arobot while another robot moves in space to weld them. The needtherefore is to have an intelligent tool at the end of the robot armwhich will adapt to the changes in the body part. The iEOAT addressesthis need by adding a higher level of intelligence and manipulationcapabilities to capital equipment used in assembly lines.

In simple terms, the iEOAT may simply be a 3D adaptive gripper, which ismounted at the end of a robot arm, which carries locating pins andclamps. In the manufacturing process, the robot moves its arm at highacceleration in six degrees of freedom. The gripper at the end of thearm moves in close proximity with the car body part, and then movesslowly such that the pins locate the part. The gripper then closes itsfingers around the body part and moves it quickly, once again, at highacceleration to the assembly point. The intelligent reconfigurable 3Dgripper has the capability of adapting the location of its “pointingfingers” (pins) and “pinching fingers” (clamps) to the size and shape ofthe body part. However, since the shape of automotive body parts arethree dimensional, the iEOAT must have the capability to adapt itsfinger's positions in three dimensions.

By using an iEOAT system in car manufacturing lines, automotivemanufacturers may run small batch production on the same assembly linewithout the penalty of excessive downtime, which otherwise may be neededto change tools from one car model to the other.

However, conventional end of arm robot tools have one or more of thefollowing limitations:

1. They consist of many accessory parts, like mounting brackets andsupport brackets, placing a burden on stocking many spare parts;

2. They lack standardization such that each tool requires custom design;

3. They are heavy, which limits the number of parts that the robot cancarry;

4. They lack stiffness, which may damage motion components, reducerepeatability;

5. They are large, which limits the number of components which may mounton the robot;

6. They have “finger” motion, which is limited to one or two dimensions,which may limit the number of car models the robot may handle with thesame tool;

7. Their stages have short travel of each finger which may limit thereach needed to handle a large number of car models;

8. They are custom made through a long engineering process consuminglong setup time;

9. They are relatively expensive since their adaptability is to alimited number of car styles and they have to change with each newproduction line or new car style change.

Accordingly, it would be desirable to provide a universal end of armrobot tool that addresses all of the above drawbacks.

SUMMARY

In one aspect of the present disclosure, an end of arm tool subassemblyis provided. The subassembly includes three identical linear drivemechanisms connected directly together to provide three directions ofmovement. Each linear drive mechanism includes a base defined by alongitudinal axis and a slide movably coupled to the base. The base hasat least one mounting surface disposed parallel to the longitudinal axisand an end mounting surface disposed perpendicular to the longitudinalaxis. The slide traverses in a direction parallel to the longitudinalaxis and has a slide mounting surface thereon. One of the identicallinear drive mechanisms is directly attached to the end mounting surfaceof the base of another linear drive mechanism to provide two of thethree directions of movement.

In a preferred embodiment, each linear drive mechanism includes threemounting surfaces arranged along the longitudinal axis on a back of thebase such the linear drive mechanism has at least five mountingsurfaces. The slide is traversable along a front of the base oppositethe back. Each of the mounting surfaces preferably includes a pluralityof mounting holes and the base preferably includes at least one recessedpocket formed in a side of the base for permitting access to themounting holes of at least one of the mounting surfaces.

Each linear drive mechanism preferably includes at least one railsupported by the base, a threaded lead screw rotatably supported by thebase, a nut threadably coupled to the lead screw and a motor forrotating the screw. The nut traverses along the longitudinal axis as thelead screw rotates and the slide is attached to the nut and is slidablycoupled to the rail. The rail and screw may be contained within aninterior compartment of the base. In this case, the linear drivemechanism further includes a flexible bellows cover substantiallycovering the interior compartment for protecting the rail and screw.

In another aspect of the present invention, an end of arm tool for arobot is provided. The tool includes at least two of the subassembliesdescribed above, wherein the base of one of the linear drive mechanismsof one subassembly is directly connected to a base of one of the lineardrive mechanisms of another subassembly to form a rigid frame member.

In a preferred embodiment, an end mounting surface of the base of one ofthe linear drive mechanisms of one subassembly is directly connected toan end mounting surface of the base of one of the linear drivemechanisms of another subassembly to form the rigid frame member. Thetool preferably includes four rigid frame members directly connected toeach other to form a rigid rectangular frame. In this manner, the frameincludes four slides traversing in a first direction and four slidestraversing in a second direction perpendicular to the first direction.

In another aspect of the present invention, a method for configuring aplurality of linear drive mechanisms, as described above, to form an endof arm tool for a robot is provided. The method includes determining theglobal coordinates of a plurality of pick-up locations of a work pieceto be manipulated by the tool, determining a required output of the toolbased on a desired path of travel of the workpiece, displaying agraphical representation of a configuration of the linear drivemechanisms arranged to perform the required output of the tool andoptimizing the configuration by determining the optimum mountingsurfaces for directly connecting one linear drive mechanism to another.

In a preferred method, a plurality of graphical representations ofoptional configurations are displayed, wherein each optionalconfiguration is displayed along with a calculated merit valuerepresenting at least one of a cost, weight, stiffness, complexity,configuration time, number of parts, reportability, drivability,programming time, teaching time, design time and implementation time.

Thus, the present invention provides a novel linear positioning stage,which can be used in an iEOAT to position a fixture part such as a pin,clamp, vise, gripper, finger or holding bracket in XYZ position, andhaving all the desirable characteristics described above.

Since typical body parts have numerous geometrical constraints, the toolof the present invention has been made small. In addition, the tool ofthe present invention is protected from harsh environments of shock,vibration, temperature changes, and welding residues. Since the robotneeds to carry it at high acceleration, the tool has been made lightweight. Since the clamping forces may need to be high, the tool of thepresent invention has been made robust and stiff. Since the tool willtypically be subjected to thermal changes, the tool of the presentinvention has been designed to accommodate thermal deformation withoutstructural distortion. The tool of the present invention is alsodesigned to be accurate, reliable and simple enough to replace in shorttime. Finally, the tool is modular in nature, thereby eliminating theneed for additional mounting brackets and accessories and thereforereducing cost.

Features of the disclosure will become apparent from the followingdetailed description considered in conjunction with the accompanyingdrawings. It is to be understood, however, that the drawings aredesigned as an illustration only and not as a definition of the limitsof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a universal end ofrobot arm tool in accordance with the present invention.

FIG. 2 is an exploded perspective view of one of the linear drivemechanisms shown in FIG. 1.

FIG. 3 is a cross-sectional view of an alternative embodiment of alinear drive mechanism formed in accordance with the present invention.

FIG. 4 is a cross-sectional view of another alternative embodiment of abase formed in accordance with the present invention.

FIG. 5 is a cross-sectional view of still another alternative embodimentof a base formed in accordance with the present invention.

FIG. 6 shows three “all-in-one” linear drive mechanisms connectedtogether according to one embodiment of the present invention.

FIG. 7 shows two linear drive mechanisms of the present inventionconnected together in a slide to slide connection.

FIG. 7a is an isolated view of one embodiment of a slide to slideconnection shown in FIG. 7 with clamps, taken along line 7 a-7 a.

FIG. 8 is a top perspective view of a linear drive mechanism of thepresent invention.

FIG. 9 is top perspective view of the linear drive mechanism shown inFIG. 8 with the slide, covers and edge guards removed.

FIG. 10 is a cross-sectional view of the linear drive mechanism shown inFIG. 9 taken along line 10-10.

FIG. 11 is an isolated view of the lead screw assembly.

FIG. 12 is an isolated view of the end caps of two linear drivemechanisms of the present invention being connected together in anend-to-end configuration.

FIG. 13 shows two linear drive mechanisms of the present inventionconnected together in a motor-to-motor configuration.

FIG. 14 is a perspective view of an assembly of linear drive mechanismsof the present invention to form an end of arm robot tool.

FIG. 15a is a top plan view of the end of arm robot tool shown in FIG. 9in a fully extended position.

FIG. 15b is a top plan view of the end of arm robot tool shown in FIG. 9in a fully retracted position.

FIG. 16 is a perspective view of an assembly of linear drive mechanismsaccording to an alternative embodiment of the present invention to forman end of arm robot tool.

FIG. 17 shows the tool of the present invention attached directly to arobot arm.

FIG. 18 shows an alternative embodiment of a tool of the presentinvention attached directly to a robot arm.

FIGS. 19a and 19b are isolated views of a crash protection device formedin accordance with the present invention.

FIG. 20 shows one possible application of two tools formed in accordancewith the present invention.

FIG. 21 is a flow chart illustrating a method for configuring an end ofrobot arm tool in accordance with the present invention.

FIG. 22A is a sample computer screen page of an iEOA softoolconfigurator for inputting information and selecting optimal XYZ stagesize for each tool (pin or clamp) for use with the method of the presentinvention.

FIGS. 22B and 22C are sample computer screen pages of an XYZconfigurator for inputting information about the mounting configurationof each XYZ set of stage, in many different configurations, andselecting the one that best meets the stiffness and precision limitationof each stage for use with the method of the present invention.

FIG. 23 is a sample computer screen page showing the optionalconfigurations with merit values generated by the method of the presentinvention.

FIGS. 24A and 24B are sample computer screen pages showing the outputgenerated by the configurator level of the software program according tothe present invention.

DETAILED DESCRIPTION

As used throughout herein, the term “tool” is defined as a device, (suchas a pin or a clamp), which is used to handle or process a product suchas an automobile body part. The term “iEOAT” is defined as anelectromechanical system consisting of frames, XYZ stages, brackets,cables, which carry tools such as clamps and pins and can bereconfigured by intelligent control system to handle and process severalproducts with different size and shape. The term “XYZ subassembly” isdefined as a system of interconnected stages and cables which aremounted to the iEOAT and carry a tool such as pin or clamp. The term“stage” is defined as an electromechanical device, which can move undercomputer control in one specific direction. The term “all in one” isdefined as a stage that can connect to another “all in one” stage and bein hundreds of different XYZ configurations without brackets. The term“universal iEOAT” is defined as an iEOAT consisting of several XYZsubassemblies, which can be interconnected to each other without anybrackets.

Referring first to FIG. 1, a universal end of arm robot tool subassembly10 according to one embodiment of the present invention is shown. Thesubassembly 10 generally includes three identical linear drivemechanisms 12, (often referred to herein as “stages,” or, in thesingular, as “a stage”), directly connected to one another in an XYZconfiguration. As will be discussed in further detail below, thesubassembly 10 can be assembled in a multitude of configurations to forma universal reconfigurable end of arm robot system, as shown in FIG. 14,where each XYZ end of arm subassembly consists of several “all in one”stages, as shown in FIG. 6, which carry an of arm tool such as a clampor a pin.

Returning to FIG. 1, a first linear drive mechanism 12 a, which drives aslide in a first direction (X-axis), is attached to the end of a robotarm (not shown). The first linear drive mechanism 12 a is directlyattached to a second linear drive mechanism 12 b, which drives a slidein a second direction (Y-axis), perpendicular to the first direction.The second drive mechanism 12 b is, in turn, directly attached to athird linear drive mechanism 12 c, which drives a slide in a thirddirection (Z-axis), perpendicular to the first and second directions. Aworkpiece manipulator 14, such as a locating pin or a gripper, isattached to the slide of the third linear drive mechanism 12 c.

As a result, the workpiece manipulator 14 is provided with threedirections (XYZ) of movement with three identical linear stages. Also,because the stages are connected directly together, there is no need foradditional mounting brackets.

FIG. 2 is an exploded perspective view of one of the identical lineardrive mechanisms 12 shown in FIG. 1. The linear drive mechanism 12includes a boxed frame 16 designed to provide a stiff and light weightconstruction to the mechanism and to resist structural deformations. Theboxed frame 16 is preferably made of aluminum or other light weight, butstrong material. The frame 16 defines a recessed compartment 18 and isformed with an exterior side extension 20 on the bottom of the frame.Extension 20 also serves as an integrated Z bracket, which stiffens thestage when mounted vertically on any mounting surface of the presentinvention.

The bottom of the boxed frame 16, together with the side extension 20,provide a mounting surface 22 for the end of the robot tool arm, or toanother linear drive mechanism. Opposite the mounting surface 22, theside extension provides a mounting surface for a motor 24, a motor cable26 and a transmission case 28.

The recessed compartment 18 defines a longitudinal space foraccommodating a lead screw 30. The lead screw 30 is supported within thecompartment 18 at its opposite ends by rotary support bushings 32, whichare fixed to the boxed frame 16, but allow for rotation of the screw 30within the compartment. The compartment 18 is designed with a minimaldepth so as to mount a nut 34 and a slide 36 in a vertical orientationwithout interference, and without extending the height more than therequired minimum.

The lead screw shaft 30 has built in friction, which eliminates the needfor a brake in vertical and horizontal orientation of the stage. It issupported by two rotary bearing on the two ends. Preferably, a bearing32 on one end is fixed to the boxed frame 16 as a thermal expansionpivot. The bearing on the other end is a bushing, which lets the leadscrew shaft expand with respect to the boxed frame without generating adistorting thermo-couple effect. The shaft, therefore, also serves as astructural element in minimizing the size and weight of the stage.

The nut 34 has an internal thread adapted to engage the external threadof the lead screw 30. When threadably attached to the lead screw 30, thenut 34 will traverse in a linear direction along the length of therecessed compartment 18 as the lead screw rotates. The slide 36 isattached to the nut 34 and extends outside of the recessed compartment18. Thus, as the nut 34 travels within the compartment 18, the slidetravels outside the boxed frame 16.

A linear rail 38 is fixed to an exterior surface of the boxed frame 16.The linear rail 38 may be a separate part attached to the boxed frame,or it may be integrally formed in an exterior surface of the frame. Anintegrally formed rail minimizes hardware, and reduces alignment withbanking surfaces and hardware and, therefore, reduces assembly time. Anintegrally formed rail further adds high stiffness to the frame 16,while reducing the risk of loose hardware due to shock and vibration.

A linear puck 40 is fixed to the slide 36 and is movably coupled to therail 38. In this regard, the puck 40 may be formed with a groove or slotsized to receive the rail in a sliding manner. The groove may include aretaining lip so as to limit movement of the puck only in the directionof the rail 38. The puck 40 and/or the slide 36 provides a mountingsurface for another linear drive mechanism 12, a tool accessory 14 orthe end of a robot arm, as desired. In this regard, the slide 36 ispreferably square in size to optimize the mounting footprint of the XYZconfigurations.

The compartment 18 and the rail 38 are covered by flexible bellows-likecovers 42 provided on opposite sides of the slide 36 in the longitudinaldirection. The bellows-like construction of the covers 42 allow thecovers to move in a telescopic fashion. One side of the covers protectsthe lead screw 30 from contamination and environmental particles such aswelding residues. The other side of the covers protects the linear rail.Both the linear rail 38 and the lead screw 30 require periodiclubrication to assure longevity and high reliability. The cover designis intended to allow quick access to the lubrication points and tointernal mounting hardware. This reduces down time and provides simpleaccess to assembly and disassembly of the stages.

As mentioned above, the motor 24 is firmly mounted to the side extension20 of the frame 16. The side extension is thus provided with clearanceholes therethrough to provide easy access to mounting holes in themotor. The motor height and width is restricted to the height of theframe but unrestricted in length. It can therefore incorporate highenough torque and feedback devices such as an encoder or a resolver,and, as may be needed, a gear reducer and a brake. The motor 24 can beany type of motor, such as geared motors, linear motors, belt drives,and linear steppers.

The drive shaft of the motor 24 engages a gear arrangement 44 containedwithin the transmission case 28. The gears of the gear arrangement 44are intended to provide parallel motor drive transmission. They may beused at a 1:1 reduction to provide transmission or they may include agear reduction ratio to increase the motor torque. This option mayeliminate the need for an integrated gear inside the motor thereforereducing cost and increasing reliability. The gears require periodiclubrication to assure longevity and high reliability. Lubrication caneasily be provided through access holes in the transmission case 28.They are preloaded through motor mounting to minimize backlash. Thetransmission case encloses the gears and provides support to the motorshaft and the lead screw shafts. It therefore adds to the robust designof the stage.

The cable 26 is integrally connected to the motor 24 for power, andfeedback. The cable 26 has connectors on the other end to connect to theuser's amplifier, which is mounted in remote. The cable is routedquickly with wide service loops to the cable support surfaces on theother stages. It is also fixed to the external walls of the frames withquick tie wrap fixation.

The embodiment shown in FIGS. 1 and 2 thus provides a tool 10 thatrequires a common stage with simple integrated parts. The tool 10 servesas a compact robust axis to be quickly integrated into robot or machinebases, or to any other stage in XY, or XYZ configurations and to the endtool of the user. The result is a compact, robust stage, which hasminimum number of parts. It has easy access to mounting for repairs andmaintenance. It is protected from the environment and gives the freedomof optimizing the motor and encoder size to fit the applicationrequirement of force and velocity.

In order to provide the desired light weight and rigidity the lineardrive mechanism 12 can be specially designed in several ways. Forexample, FIG. 3 shows a cross-section of an alternative embodiment of alinear drive mechanism 12 a in which two rails 38 a and 38 b areprovided on perpendicular exterior surfaces 46 a and 46 b of a boxedframe in the form of a solid base 16 a.

In the embodiment shown in FIG. 3, the base 16 a is preferablymanufactured by extrusion of a light-weight, but rigid material, such asaluminum. The base 16 a includes an integrated Z-bracket 48, whichdefines a compartment for housing the motor 24 and the cable.

As mentioned above, one linear rail 38 a is mounted to one exteriorsurface 46 a of the base 16 a, while another linear rail 38 b is mountedon a second exterior surface 46 b of the base, which is perpendicular tothe first surface 46 a. As described above, each rail 38 a, 38 b mayhave one or more moving pucks 40 a, 40 b. The pucks 40 a, 40 b togetherare connected to a linear slide 36, which may carry a process movingload 50, or other motion accessories, such as a motion stop clamp 52.

The advantage of the perpendicular rail set 38 a, 38 b is to minimizethe puck force reactions to external forces and moments in alldirections. It should also be noted that the advantage of the two railson two perpendicular planes is the considerable reduction of momentloading of the pucks 40 a, 40 b, and the reduction of reaction forces toexternal moments due to maximizing the possible distance between thepucks.

To further provide the desired light weight and rigidity to the lineardrive mechanism 12, the base itself can be specially designed in severalways. For example, FIG. 4 shows a cross-section of another alternativeembodiment of a base 16 b in the form of an extrusion having integralstiffeners.

The base 16 b shown in FIG. 4 is an extrusion for a light weightpositioning stage, which maximizes the stiffness to bending in normaland transverse directions as well as the stiffness in torsion. This isaccomplished by providing integral thin wall stiffening ribs in bothnormal and inclined directions. Specifically, the base includes externalstiffening ribs 54, arranged in a square configuration forming aperiphery of the base, as well as internal stiffening ribs 56 arrangedin a cross configuration within the external ribs.

The base 16 b is further preferably formed with perpendicular railmounting surfaces 58 a, 58 b, which are an integral part of the externalribs 54. The internal ribs 56 form an inside compartment 60, whichaccommodates the actuator mechanism, such as the ballscrew or the linearmotor (not shown). Both the external and internal ribs 54, 56 alsoinclude threaded mounting holes 62 at end faces thereof for mounting endcaps (not shown). At least one of the external ribs 54 is further formedwith at least one integral mounting rib 64, which serves as a Z bracket,for mounting the base to a robot arm or to another base.

FIG. 5 shows another embodiment of a base 16 c in the form of anextrusion with crossed aluminum stiffeners and compartments for“sandwiched” stiffeners of composite material (e.g. carbon fiber) on itsperiphery. In particular, the base 16 c is an aluminum extrusion havingan outer wall 66 forming a rectangular periphery. Two linear rails 38 a,38 b are mounted to an outer face of one of the walls, and each rail hasa puck 40 a, 40 b coupled to the rail in a sliding manner.

The base 16 c of this embodiment further includes an inner wall 68spaced from the outer wall 66 to thereby form a compartment between theinner and outer wall. The inner wall 68 serve as stiffeners for bendingand torsion and the compartments 70 receive composite stiffeners 72 tofurther provide stiffness to the base. The stiffeners 72 may befastened, for example by glue, pins or bolts, to the enclosedcompartment defined between the inner and outer walls 66, 68. Togetherthey form a “sandwich” configuration, which provides enhanced stiffnessand rigidity in bending and torsion.

The base 16 c is further preferably formed with cross stiffeners 74,which provide additional rigidity to bending and twist, and a circularstiffener 76. The circular stiffener 76 forms a compartmentcommunicating with the exterior of the extrusion for accommodating thelead screw, belt or linear motor (not shown).

In all embodiments, the base is uniquely designed to provide maximummodularity benefits to the linear drive mechanism of the presentinvention. Specifically, as shown in FIG. 6, the base and slide of thelinear drive mechanism of the present invention provide five (5)mounting surfaces 1, 2, 3, 4, 5 for mounting to a robot arm or toanother linear drive mechanism. The slide 36 of each drive mechanismprovides a first mounting surface 1, the longitudinal end 78, oppositethe motor, provides a second mounting surface 2 and the back surface 80,opposite the slide 36, provides three separate mounting surfaces 3, 4, 5spaced along the length of the base. Thus, the linear drive mechanism ofthe present invention allows for numerous assembly configurations.

For example, FIG. 6 shows three identical linear drive mechanisms 12 a,12 b, 12 c connected together in one arrangement. A first linear drivemechanism 12 a is connected to the end 78 of a second linear drivemechanism 12 b via its third mounting surface provided on the back faceof its base. The second linear drive mechanism 12 b is connected to athird linear drive mechanism 12 c via a slide to slide connection.Specifically, the first mounting surface 1 provided on the slide of thesecond linear drive mechanism 12 b is attached to the first mountingsurface 1 provided on the slide of the third drive mechanism 12 c. Anyone of the remaining mounting surfaces can be attached directly to arobot arm. Similarly, a workpiece manipulator, such as a pin or gripper,can be mounted to one of the mounting surfaces for full XYZ travel.

FIG. 7 shows in further detail the multiple mounting capabilities of thelinear drive mechanism of the present invention. Specifically, FIG. 7shows a first linear drive mechanism 12 a connected to a second lineardrive mechanism 12 b in a slide-to-slide connection. This can beaccomplished by directly fastening the slides together with suitablebolts.

As can be seen in FIG. 7, the back surface 80 of each extruded base 16has a plurality of mounting holes 82 formed therein. The mounting holes82 are equally spaced along the length of the base 16 and are providedadjacent both lateral edges of the base at equal distances apart. Inthis manner, the back surface 80 of the base 16 can be divided intothree separate mounting surfaces 3, 4, 5 spread out along the length ofthe base.

To provide access to these mounting holes 82 from both directions, thesides of each base 16 are formed with access pockets 84 having a depthso as to communicate with the mounting hole and to enable insertion andtightening of a mounting bolt.

The bases 16 shown in FIG. 7 are also provided with an end cap 86fastened to one longitudinal end thereof. The end cap 86 can be fastenedwith bolts engaged with threaded holes formed in the end of the base, asdescribed above. The end cap 86 includes additional mounting holes 88formed therein to provide the second mounting surface 2 for the drivemechanism 12.

For example, as shown in FIG. 8, the end cap 86 includes mounting holes88 that have a spacing in the lateral direction of the base 16 thatmatches the lateral spacing of the mounting holes 82 on the back surface80 of the base 16. The spacing in the other direction for all of themounting holes will also match so as to enable total mounting capabilitybetween all mounting surfaces 1, 2, 3, 4, 5 of multiple linear drivemechanisms.

The slide 36 also includes mounting holes 89 for mounting the slide toany of the mounting surfaces of another linear drive mechanism. Themounting holes 89 of the slide will preferably have an arrangement ofalternating threaded holes and counter-bored through holes so as toallow a bolted connection without nuts. The lateral spacing between themounting holes 89 provided on the slide 36 matches the lateral spacingof the end cap mounting holes 88 and the base mounting holes 82. Thespacing between adjacent threaded holes of the slide in the otherdirection will match the longitudinal spacing of all of the othermounting holes. Likewise, the spacing between adjacent counter-boredholes of the slide in the other direction will match the longitudinalspacing of all of the other mounting holes. This will allow forselection of one set of holes in one slide to a cooperating set ofmounting holes in the other slide.

As can also be seen in FIG. 8, the access pockets 84 of the base 16 havea depth to also enable access to the mounting holes 88 of the end capand the mounting holes 89 of the slide. This will allow insertion of abolt from one direction and a cooperating nut from the other directionfor fastening two mounting surfaces together.

The front surface 90 of the base 16, opposite the back surface 80, mayalso be provided with a plurality of mounting holes 92 similar to theback surface. These mounting holes 92, which are also accessible via theaccess pockets 84 allow for insertion and tightening of bolts for onemethod of mounting one slide 36 to another. After assembly, the mountingholes 92 may be covered by edge guards 94, as shown in FIG. 8.

FIG. 7a shows another method for attaching the slide 36 of a firstlinear drive mechanism 12 a to the slide 36 of another linear drivemechanism 12 b. In this embodiment, a pair of clamping fingers 94 ismounted to each slide 36 for engagement with the opposite slide. Eachslide 36 is also formed with a retaining rib 96 adapted to be capturedand retained by the clamping finger 94 of the opposite slide. Theclamping fingers are releasably attached to their respective slides byconventional bolts or screws. With the retaining rib 96 of one slideretained by the clamping finger 94 of the other slide, the two slidescan be secured together.

Returning to FIG. 8, an alternative embodiment for mounting the motor 24is shown. In this embodiment, the motor 24 is mounted directly to theend of the base 16 opposite the end cap 86. This provides a more compactlinear drive mechanism, which eliminates the need for a side bracket anda transmission case. In this embodiment, the third mounting surface 3,provided on the back face 80 of the base 16, is disposed adjacent themotor 24, the fourth mounting surface 4 is provided midway between themotor and the end cap 86, and the fifth mounting surface 5 is disposedadjacent the end cap, which provides the second mounting surface 2.

FIG. 9 shows the linear drive mechanism 12 shown in FIG. 8, with theslide, covers and edge guards removed. In this drawing, it can be seenhow the base 16 is formed with a central recessed compartment 18defining a longitudinal space for accommodating the lead screw 30. Thelead screw 30 is supported within the compartment 18 at its oppositeends by rotary support bushings 32, and a brake, which are fixed to thebase 16, but allow for rotation of the lead screw 30 within thecompartment. The motor 24 is coupled to one end of the lead screw 30 forrotating the lead screw. The compartment 18 also accommodates the nut34, which is threadably coupled to the lead screw 30 for movement up anddown the length of the compartment as the lead screw rotates, asdescribed above.

Two linear rails 38 a and 38 b are fixed to a front surface of the base16 and two pucks 40 are slidably coupled to each rail. The slide 36 (notshown in FIG. 9) is, in turn, attached to both the nut 34 and the pucks40 so that, as the nut is driven up and down the length of thecompartment 18, the slide travels along the rails via the pucks. Thecovers 42 (not shown in FIG. 9) protect both the interior compartment 18and the rails 38 a, 38 b.

FIG. 10 is a cross-sectional view of the linear drive mechanism 12 shownin FIG. 9. As can be seen in FIG. 10, the compartment 18 is designedwith a minimal depth so as to mount the nut 34 in a vertical orientationwithout interference, and without extending the height more than therequired minimum.

In this regard, a specially designed nut 34 is preferably provided toallow for a minimum depth of the compartment 18. As shown in FIG. 11,the specially designed nut 34 includes an end plate portion 34 a and aslide support portion 34 b. The end plate portion 34 a and the slidesupport portion 34 b may be formed integrally, or they may be separateparts attached together. The end plate portion 34 a is formed with athreaded hole 34 c to engage the external thread of the lead screw. Theslide support portion 34 b has an upper surface 34 d having threadedmounting holes for mounting the slide. The end plate portion 34 a has acurved bottom 34 e opposite the upper slide mounting surface 34 d. Thecurved bottom 34 e is machined to match the bottom circular curvature 18a of the recessed compartment 18.

Returning to FIG. 10, it can be seen that the base 16 is designed toprovide the desired light weight and rigidity to the linear drivemechanism 12. Thus, the base 16 is manufactured by extrusion of alight-weight, but rigid material, such as aluminum, and includesinternal integral thin wall stiffeners in both normal and inclineddirections. Formed centrally in the base is a circular stiffener formingthe curved-bottom compartment 18. External stiffeners form the outerperiphery of the base, including the back surface 80 having the mountingholes 82, and further define the access pockets 84 described above. Theexternal stiffeners further include threaded mounting holes 62 at endfaces thereof for mounting the end cap at one end and the motor at theopposite end.

By providing multiple mounting surfaces, the universal linear drivemechanisms of the present invention can be configured in many differentways. One of the unique ways the linear drive mechanisms may beconfigured is by an end-to-end connection. Specifically, FIG. 12 showshow the second mounting surface 2 provided by the end cap 86 can beutilized to mount one linear drive mechanism to another end-to-end. Asdescribed above, the base 16 of each linear drive mechanism is providedwith a recessed access pocket 84, which allows for insertion of a bolt96 through a mounting hole 88 of the end cap 86 of one drive mechanismfor threaded engagement with a nut (not shown) residing in the accesspocket 84 of the base of the other drive mechanism.

In an alternative embodiment, the motor 24 of each drive mechanism canbe provided with a flange 98 that allows for motor-to-motor connectionbetween two drive mechanisms 12 a 1, 12 a 2, as shown in FIG. 13.

In addition to end-to-end connections, the second mounting surface 2provided on the end cap 86, as shown in FIG. 12, or on the motor 24, asshown in FIG. 13, further allows for direct perpendicular mounting oflinear drive mechanisms without the need for additional angle bracketsor mounting hardware between the stages themselves. This permits trueorthogonal mounting of linear drive mechanisms for three directions(X-Y-Z directions) of movement for the workpiece manipulator withrespect to the robot arm.

For example, FIGS. 14, 15 a and 15 b show a configuration of twenty-four(24) linear drive mechanisms 12 connected in triplets to form an end ofarm tool 100 carrying workpiece manipulators in the form of four fingers102 and four clamps 104. The tool 100 shown in FIGS. 14, 15 a and 15 bis made by first connecting the bases of eight linear drive mechanisms12 a 1, 12 a 2, 12 a 3, 12 a 4, 12 a 5, 12 a 6, 12 a 7 and 12 a 8together to form a rigid frame 106. Preferably, two linear drivemechanisms are connected end-to-end via their end caps to form fourpairs. The back face of each base of a connected pair is then attachedto a back face of a base of another connected pair so that a rigidsquare frame 106 is formed. The frame 106 thus formed is directlyconnected to an end of a robot arm 108, as shown in FIGS. 15a and 15 b.

As can be seen in the drawings, the slides of two opposite pairs ofconnected drive mechanisms forming the frame 106 face in one directionand the slides of the other two opposite pairs of the frame face in theother direction. Also, the slides of two opposite pairs of connecteddrive mechanisms travel back and forth in a first direction(X-direction), while the slides of the other two opposite pairs travelin a direction perpendicular to the first direction (Y-direction).

Attached to each slide of the drive mechanisms 12 a 1, 12 a 2, 12 a 3,12 a 4, 12 a 5, 12 a 6, 12 a 7 and 12 a 8 forming the base frame 106 isa second level drive mechanism 12 b 1, 12 b 2, 12 b 3, 12 b 4, 12 b 5,12 b 6, 12 b 7 and 12 b 8. In a preferred embodiment, the slides of thesecond level drive mechanisms 12 b 1, 12 b 2, 12 b 3, 12 b 4, 12 b 5, 12b 6, 12 b 7 and 12 b 8 are respectively connected directly to the slidesof the frame drive mechanisms 12 a 1, 12 a 2, 12 a 3, 12 a 4, 12 a 5, 12a 6, 12 a 7 and 12 a 8. Each second level drive mechanism 12 b 1, 12 b2, 12 b 3, 12 b 4, 12 b 5, 12 b 6, 12 b 7 and 12 b 8 has a slide thattravels in a direction perpendicular to the direction of travel of theslide to which it is attached.

Attached to each end cap of the second level of drive mechanisms 12 b 1,12 b 2, 12 b 3, 12 b 4, 12 b 5, 12 b 6, 12 b 7 and 12 b 8 is a slide ofa respective third level drive mechanism 12 c 1, 12 c 2, 12 c 3, 12 c 4,12 c 5, 12 c 6, 12 c 7 and 12 c 8. Accordingly, the third level drivemechanisms 12 c 1, 12 c 2, 12 c 3, 12 c 4, 12 c 5, 12 c 6, 12 c 7 and 12c 8 travel in a third direction (Z-direction) perpendicular to the firstdirection (X-direction) and second direction (Y-direction).

Attached to the end cap 86 of each third level drive mechanism is one ofa finger 102 or a clamp 104. As a result of such assembly, each finger102 and each clamp 104 is provided with three directions of travel (X, Yand Z directions). This can be seen in FIG. 15a , showing all of thelinear drive mechanisms in their fully extended state, and FIG. 15b ,showing all of the drive mechanisms in their retracted state.

The linear drive mechanisms of the present invention can be assembled invarious ways. For example FIG. 16 shows a configuration of an end of armrobot tool 100 a wherein one or more directions of travel of the pins102 and/or clamps 104 are not perpendicular to each other. This can beachieved by providing inclined mounting surfaces 108 to one or moreslides, as desired.

An alternative embodiment for forming the frame 106 a is also shown inFIG. 16. In this embodiment, two pairs of end-to-end connected lineardrive mechanisms are provided, as described above. However, the lineardrives of the other two pairs of linear drive mechanisms are connectedtogether via the back surfaces of their respective bases. Also, the endcaps provided at the opposite ends of this pair of linear drivemechanisms is attached to a respective back surface of the end-to-endconnected linear drive mechanisms.

Thus, as shown in FIG. 17, the present invention provides a systemconstructed entirely as a frame structure 106 made of only one type of asmall “all-in-one” positioning stage. The frame structure 106 isattached directly to a robot arm 110, without the need for any end ofrobot arm structures, or stiffening brackets.

Each linear drive mechanism has several mounting surfaces, all of whichare capable to interconnect by sets of access and mounting holes, whichallow the linear drive mechanism itself to be used as both a structuralelement, supporting multiple XYZ stages in flat, upright or tiltedorientations, as well as to operate as an XYZ positioning system, forpositioning process tools. Each XYZ stage may carry a tool, such as aregistration pin or a clamp, depending on the specific applications.

FIG. 18 shows another alternative embodiment of a frame structure 106 bassembled from only four first-level “base” or “frame” linear drivemechanisms 12 a 1, 12 a 2, 12 a 3 and 12 a 4. In this embodiment, thebases of four linear drive mechanisms are connected perpendicularly toeach other to form a rigid square frame 106 b. Specifically, the end capof each base is connected to one of the outer bottom mounting surfacesof another base so that a rigid square frame 106 b is formed. The frame106 b thus formed is directly connected to an end of a robot arm 108.

Further connection of second-level linear drive mechanisms to the frame106 b, and third-level linear drive mechanisms to the second-levellinear drive mechanisms, as described above will result in a smalluniversal iEOAT consisting of a base of 4 stages with a total of twelveXYZ stages supporting four tools 104. It can be appreciated that FIG. 18shows only one of thousands possible configurations with the same twelvestages without the use of any brackets.

FIG. 18 further shows collision protection devices 116 provided betweenthe base mounting surfaces of connected linear drive mechanisms. As alsoshown in further detail in FIGS. 19a and 19b , the collision protectiondevice 116 includes two spring preloaded plates 118 a, 118 b, which canbe mounted any where between any two stages in their XYZ configurationand serve to absorb shock by accidental robot collision without damagingthe stage.

The plates 118 a and 118 b are adapted for mounting to a respectivemounting surface of a linear drive mechanism. The plates 118 a and 118 bare also kinematically coupled to one another via flexing elements 120,such as springs, having a sufficient resiliency so as to createcompliance for impact absorption and some lateral and angulardisplacement between the plates.

The crash protection device 116 may be an optional part of the universaliEOAT base frame connecting between some of the base stages (at leastone per system), or it may be mounted as part of any XYZ stage at aconvenient location. The flexing elements 120 are designed to collapseabove the maximum expected process load, but less than the yield pointof the stages. A small deflection at the base of the universal iEOATwill allow a much larger deflection at the outer distance, where theaccidental crash may most likely hit an exposed stage.

The end of arm robot tool of the present invention can be used in manyapplications, and can be customized to perform many functions. FIG. 20,for example shows a configuration which uses the same universal iEOAT,both as a part handler 100L (on the left) and a Geo platform 100R (onthe right). Each universal iEOATs 100L, 100R, are carried by arespective robot 110L, 110R. As shown, the robot on the right 110R picksa main car body part 112 with the universal iEOAT 100R via multiple pinsand clamps, and positions the part in a given orientation in space,which was taught to the robot 110L.

The robot 110L on the left picks up, with the same universal iEOAT 100L,two independent stiffening parts 114 to be welded to the main part 112.The robot 110L on the left inserts the two locating holes of the smallstiffener part into the two exposed pins on the main part, while thesecond stiffener is retracted. A welding robot (not shown) then weldsthe smaller stiffener to the main part. After welding the pins of thesmaller part, the pins holding the smaller part retract and the sameprocess repeats for the second stiffener.

After both stiffeners are welded, the main robot 110R on the rightunloads the assembled part and loads a new part 112. The handling roboton the left 110L returns to the loading station and picks up two newparts 114.

The advantages provided by this application include: 1) Eliminates theneed for a floor mounted geometric frame therefore saving cost and floorspace; 2) The universal iEOAT can handle several parts on one roundtrip, therefore saving time of the handling robot going back and forthto pick individual parts; 3) Uses the same universal iEOAT for both mainpart support (acting as the geo frame) and for the part handling,therefore, saving cost of customization of part grippers and geo frames,with one standard iEOAT system; 4) The same robot can change rolesservicing different parts on its 4 sides, (e.g., acting as a parthandler on the left and as a Geo stand on the right), therefore, givingflexibility of plant automation layout and saving cost of robots andtooling; 5) The two robots can rotate the part 360 degrees and presentit to a smaller welding robot and saving the cost of a larger weldingrobot.

In another aspect of the present invention, a method for assemblingmultiple linear drive mechanisms to perform a specified function isprovided. The method is utilized for constructing a reconfigurableuniversal multi-axes intelligent end of arm tool (iEOAT), which isparticularly adapted for high productivity of automotive manufacturingprocesses. This method is preferably implemented with an interactiveonline software program referred to herein as “the softool” and/or “theconfigurator.” Both software programs are intended to assist the processengineer in selecting the optimal configuration for the iEOAT, through aquick interactive process.

The method for assembling multiple linear drive mechanisms according tothe present invention has several objectives. First, the configurationparameters must be defined. This involves defining the desired locationof the tools of each work piece, then calculating the required travel inthe X, Y, and Z directions for all of the XYZ stages of the presentinvention. This further involves defining the teach point location ofthe robot that carries the iEOAT. Once the travel of the XYZ for eachtool is determined, it is desired to determine the best configurationfor mounting and support surfaces of each stage such that deformationsunder load are minimized and the precision is maximized.

More specifically, referring to the flow chart shown in FIG. 21, themethod according to the present invention generally involves two phases.In the first phase (“softool phase”), the stage travels for each tool(pin or clamp) are selected using an iterative optimization process. Inthe second phase (“configurator phase”), the selected stage travel ofeach tool is optimized in an iterative process for their mountingconfigurations.

The first phase begins with the step 200 of determining locations forall contact points of tools for all of the workpieces to be manipulatedby the tool. This information can be provided by a plant engineer as XYZcoordinates referenced to a global coordinate system based on the plantenvironment. The coordinates include contact points for clamps and/orhole centers for locating pins. These coordinates define the location ofthe workpiece to be picked-up.

In step 201, these coordinates are input into fields of a computer workscreen, as shown in FIG. 22A. As can be seen in FIG. 22A, a computersoftware program generates a screen that includes fields that can bepopulated with the respective global coordinate for each body part modeland each tool for each model

In step 202, Softool provides an output of the required XYZ travel ofeach tool in the input. This will typically include the required travelof the tool in the XYZ direction for each workpiece (e.g. body partstyle). In step 203, the center position of the tool within its travelrange and the teach points of the robot end of arm (EOA) interface tothe end of arm tool (EOAT), etc. A sample computer screen page forinputting such information is shown in FIG. 22B.

As can be seen in FIG. 22B, a computer software program generates achart which shows stage travel and location, as well as robot positionsfor single teach points and multiple teach points. FIG. 22C represents apictorial view of information in FIG. 20B including a drawing with theXY foot print of each pin, pin center location, and robot teach pointfor a single teach point and for multiple teach point options. Step 204of the process involves a review of the drawing and a decision ifimprovement is required. Such graphical representation can assist thedesigner to visualize the location and movement for each stage.

If changes in stage sizes are required, an “optimizer” sub-routine isrun by the computer software program in step 205. The optimizersub-routine can offer the designer the option to insert an offset to therobot. Such an offset requires a new teach point, but will make therequired travel of some stages less and some stages higher. This featureis helpful in case there is a limitation of available all in one stagetravel.

After a choice is made for one tool, a repeat stage selection is donefor a new tool with, possibly, a new XYZ stage length.

Phase 2 (“configurator phase”) begins with step 206. The outputinformation from the softool then becomes an input to the configurator,which runs at step 206 with the following steps. The XYZ travel of eachtool, as found in the Softool, is entered in step 207 to theConfigurator work screen, as shown in FIG. 24A. Then, the output of theConfigurator, as shown in FIG. 24B, is reviewed in step 208. In step209, the compatibility of the defection of the stage under load ischecked against maximum recommended deflection. In step 210, themounting configuration may change in an iterative process of searchingfor the stiffest mounting configuration, which is then selected in step211. The process then repeats for the XYZ configuration of the nexttool, until all configurations are done.

FIG. 23 shows an example of various mounting configurations of 4 toolsincluding a set of metrics that may be used to further rate eachconfiguration with respect to their specific merits. As can be seen inFIG. 23, computer software programmed to carry out the method of thepresent invention will process the data input to generate visualrepresentations of a number of stage configurations (i.e., numbers andarrangements of linear drive mechanism) that can perform the desiredfunctions. The computer program further weights each possibility basedon a number of criteria, which may include cost of the system, weight,stiffness, complexity, configuration time, number of parts,repeatability, durability, programming time, teaching time, iEOAT designtime, iEOAT implementation time. These merits of value can then bedisplayed in a comparison chart, as shown in FIG. 23.

Thus, the method according to the present invention allows the designerto design a very stiff frame made of interconnected stages. Other stagescan be mounted in hundreds of different configurations to best fit theapplication, all with minimal or no brackets or heavy supporting frames.The software tools provide the designer with a quick way of analyzingthe best XYZ stage travel and mounting configuration to result in highstiffness and high precision of the iEOAT tools, such as pins andclamps. In addition, the entire structural frame may be reconfigured toserve a different class of body parts. The entire structure is extremelystiff since it employs several stages in carrying the process loads indifferent directions. Therefore, weak spots of the small stage, such asroll stiffness, are not being expressed when working in parallel withother stages, which resist the load in direction of higher stiffness.

The entire structure is light-weight, which is ideal for robot handlingsince only the stages participate in the structure without anyadditional mounting frames or stiffening brackets.

While various embodiments of the present invention are specificallyillustrated and/or described herein, it will be appreciated thatmodifications and variations of the present invention may be effected bythose skilled in the art without departing from the spirit and intendedscope of the invention.

1. An end of arm tool subassembly comprising three identical lineardrive mechanisms connected directly together to provide three directionsof movement, each linear drive mechanism comprising; a base defined by alongitudinal axis, the base having at least one mounting surfacedisposed parallel to said longitudinal axis and an end mounting surfacedisposed perpendicular to said longitudinal axis; and a slide movablycoupled to said base, said slide traversing in a direction parallel tosaid longitudinal axis and having a slide mounting surface, wherein oneof said identical linear drive mechanisms is directly attached to theend mounting surface of the base of another linear drive mechanism toprovide two of said three directions of movement.
 2. A subassembly asdefined in claim 1, wherein each linear drive mechanism comprises threemounting surfaces arranged along said longitudinal axis on a back ofsaid base such that said linear drive mechanism has at least fivemounting surfaces, and wherein said slide is traversable along a frontof said base opposite said back.
 3. A subassembly as defined in claim 1,wherein each of said mounting surfaces comprise a plurality of mountingholes, and wherein said base comprises at least one recessed pocketformed in a side of said base for permitting access to said mountingholes of at least one of said mounting surfaces.
 4. A subassembly asdefined in claim 1, wherein each of said linear drive mechanisms furthercomprises: at least one rail supported by said base; a threaded leadscrew rotatably supported by said base; a nut threadably coupled to saidlead screw, said nut traversing along said longitudinal axis as saidlead screw rotates; and a motor for rotating said lead screw, whereinsaid slide is attached to said nut and slidably coupled to said rail. 5.A subassembly as defined in claim 4, further comprising a brake coupledto a shaft of said lead screw.
 6. A subassembly as defined in claim 4,wherein said rail and said screw are contained within an interiorcompartment of said base, and wherein each of said linear drivemechanisms further comprises a flexible bellows cover substantiallycovering said interior compartment for protecting said rail and screw.7. A subassembly as defined in claim 1, further comprising a resilientcrash protection device mounted between two linear drive mechanisms forabsorbing an impact force therebetween.
 8. An end of arm tool for arobot comprising at least two subassemblies as defined in claim 1,wherein the base of one of said linear drive mechanisms of onesubassembly is directly connected to a base of one of said linear drivemechanisms of another subassembly to form a rigid frame member.
 9. Atool as defined in claim 8, wherein an end mounting surface of the baseof one of said linear drive mechanisms of one subassembly is directlyconnected to an end mounting surface of the base of one of said lineardrive mechanisms of another subassembly to form said rigid frame member.10. A tool as defined in claim 8 comprising four rigid frame membersdirectly connected to each other to form a rigid rectangular frame, suchthat said frame comprises four slides traversing in a first directionand four slides traversing in a second direction perpendicular to saidfirst direction.
 11. A method for configuring a plurality of lineardrive mechanisms to form an end of arm tool for a robot, wherein eachlinear drive mechanism comprises a base, a slide linearly traversablewith respect to the base, and a plurality of mounting surfaces, themethod comprising: determining the global coordinates of a plurality ofpick-up locations of a work piece to be manipulated by the tool;determining a required output of the tool based on a desired path oftravel of the workpiece; displaying a graphical representation of aconfiguration of the linear drive mechanisms arranged to perform therequired output of the tool; and optimizing the configuration bydetermining the optimum mounting surfaces for directly connecting onelinear drive mechanisms to another.
 12. A method as defined in claim 11,wherein a plurality of graphical representations of optionalconfigurations are displayed.
 13. A method as defined in claim 12,wherein each optional configuration is displayed along with a calculatedmerit valve representing at least one of a cost, weight, stiffness,complexity, configuration time, number of parts, reportability,drivability, programming time, teaching time, design time andimplementation time.
 14. (canceled)
 15. (canceled)
 16. (canceled) 17.(canceled)
 18. (canceled)